Selective exfoliation of single-layer graphene from non-uniform graphene grown on Cu

Abstract

Graphene growth on a copper surface via metal-catalyzed chemical vapor deposition has several advantages in terms of providing high-quality graphene with the potential for scale-up, but the product is usually inhomogeneous due to the inability to control the graphene layer growth. The non-uniform regions strongly affect the reliability of the graphene in practical electronic applications. Herein, we report a novel graphene transfer method that allows for the selective exfoliation of single-layer graphene from non-uniform graphene grown on a Cu foil. Differences in the interlayer bonding energy are exploited to mechanically separate only the top single-layer graphene and transfer this to an arbitrary substrate. The dry-transferred single-layer grapheme showed electrical characteristics that were more uniform than those of graphene transferred using conventional wet-etching transfer steps.

Targeted removal of copper foil surface impurities for improved synthesis of CVD graphene

“…The variability of properties between different Cu foils, and between multiple samples of one Cu foil, demonstrates the need for representative samples with consistent properties to overcome the risk of spurious results. The confirmation of a surface coating on AA-99.8C raises some concern about the use of this foil both with and without significant cleaning procedures [43][44][45].…”

Controlling Interfacial Reactions and Intermetallic Compound Growth at the Interface of a Lead-free Solder Joint with Layer-by-Layer Transferred Graphene

“…Therefore, we believe that the differences in the Raman spectra are attributed to the organic residues of the flux at the interface after the reflow process. There have been reports that the organic residues could affect the Raman spectra in previous studies. − …”

Toward Scalable Growth for Single-Crystal Graphene on Polycrystalline Metal Foil

“…First, a small piece of single-crystalline monolayer graphene (1 × 1 cm 2 ) serving as a mother substrate for graphene seeds was grown on a Ge(110) substrate. After a Au film was deposited on the as-grown graphene, the Au-deposited graphene was transferred onto a SiO 2 /Si substrate by a clean, dry transfer method. , The transferred Au/graphene was patterned to form an array of 10 μm size dots with 50 μm spacing (Figure b and Supporting Information Figure S2). By using a polymethylsiloxane (PDMS) stamp coated with the thermal-releasable polymer layer, which has arrays of micropillars with a diameter of 30 μm and an interval of 30 μm, the Au/graphene seed arrays with uniform spacing can be selectively picked up and released onto the polycrystalline Pt substrate (Figure c,d).…”

“…Au thin film (40 nm) was deposited on the single-crystalline graphene synthesized on a Ge(110) substrate by a thermal evaporator. The Au-deposited graphene was mechanically exfoliated from Ge(110) and transferred on the SiO 2 /Si substrate by dry transfer. , The seed patterning was performed using a photoresist (PR, AZ1514E) coating, prebaking (95 °C, 1 min), UV exposure, development (MF319, 90 s), a DI rinse, and postbaking (100 °C, 1 min) processes. To define the seed array structure, the exposed Au thin film and underlying graphene were then etched using KI/I 2 solution and oxygen plasma (10 min, 100 sccm, 100 W), respectively.…”